It has previously been proposed to use albumin proteins such as whey and egg white to substitute for fat to a greater or lesser extent so as to produce low-fat food products for which there is an ever increasing demand. It is however particularly important for safety reasons, when using albumin to ensure that it is properly pasteurized. When albumin is subjected to heat treatment, though, there is a considerable risk of the albumin coagulating and/or being hydrolyzed, which generally results in processing difficulties and adverse effects on the texture, mouth-feel, and other properties of the final food product in which it is used. Conventionally therefore manufacturers have gone to considerable lengths to avoid any denaturation of the albumin as far as possible in order to prevent the albumin from coagulating.
Whey is generally defined as the liquid byproduct from the manufacture of cheese and casein by the acid or rennet coagulation of milk. The whey obtained from acid coagulation is called acid whey and that obtained from rennet coagulation, sweet whey. Liquid whey generally consists of the following: 88.7% w/v water, 0.9% w/v protein (mostly lactalbumin), 5.1% w/v lactose, 0.3% w/v fat and 0.5% w/v minerals. The total solids content typically is in the range 5–10% w/v. Large scale drying techniques have in recent years been developed, which make the production of dry whey solids both technically possible and economically feasible. A large proportion of dried whey produced is still used as animal feed. Utilization of dried whey in food compositions for human consumption has been limited because of functional deficiencies inherent in dry whey solids such as insolubility. In most industrial processes the whey protein is purified by advanced ultrafiltration, micro-filtration or ion-exchange techniques. This is followed by conventional spray-drying procedures. The whey protein thus obtained is not denatured and will form gels or coagulate when heated or acidified.
Liquid egg white typically comprises 88.5% w/v water and 9.8% w/v ovalbumin, with the balance made up of minor amounts of fat, minerals and glucose. Spray-dried native egg white and whey protein are often difficult to dissolve in water, coagulate when heated and acidified and have poor emulsification properties. Native whey and egg white do not denature when dried using conventional spray drying techniques: “although spray-dried products comes into contact with hot air, at no stage during the process does the product temperature become high enough to cause product denaturation” Spray drying handbook, Keith Masters, 5th edition. Publishers: Longman Scientific & Technical”. Whole dry whey generally contains usually 12% w/v by weight of protein. It is an object of the present invention to avoid or minimize one or more of the above disadvantages.
It has now surprisingly been found that by carefully controlling the denaturation of albumin during pasteurization thereof, it is possible to obtain a fat replacement product which is safe and has very good processing characteristics, whilst being substantially free of coagulation or degradation resulting from hydrolysis thereof.